Wessex Water has recently began work on a new extension to Allington Reservoir in Wiltshire, as part of its ‘Water Supply Grid’ programme, which aims to improve supply to customers without the development of new resources.
The £3.5 million scheme, delivered by the main contractor May Gurney, will increase the reservoir’s capacity by 5 million litres. Problems with the integrity of the existing pipeline used for the clean out of the reservoir along with the increased capacity from the extension of Allington meant that the pipeline needed to be replaced as part of the reservoir upgrade.
The new 1.8km pipeline will serve both the existing reservoir and the extension, discharging the water from the clean out operation into a larger stream further away from the site.
Material suppliers were involved during the design period to stimulate innovative proposals and promote savings. Pipe specified during the feasibility stage and manufactured by GPS PE Pipe Systems (gpsuk.com), was delivered to site in just four vehicle loads. Explains Alex Brownlow from May Gurney: “By providing pipe in longer lengths (18m), the supplier helped us reduce the number of deliveries and on-site welds by 30%. The reduced number of joints also helps underpin pipeline integrity.”
The pipe lengths were joined by butt fusion welding and, at road crossings, by Durafuse electrofusion couplers. The thin (18mm) pipe wall has made the jointing process still quicker while providing a sufficient pressure rating for the required flow rate.
The May Gurney Team installed the pipe in an open cut operation and the durability and flexibility of the pipe provided key operational advantages in that regard. Alex Brownlow continues: “In some areas the trenches are around 3.5m deep so specification of tough yet flexible Excel PE100 pipe made pipe laying easier and faster.”
The Allington Reservoir upgrade is due for completion before Christmas 2013 and will form an important element in the Wessex Water eight-year ‘Water Supply Grid’ scheme, which includes a total of 20 individual projects across Somerset, Wiltshire and Dorset.